<button class="shadow__btn">
    uiverse
</button>
<style>
/* From Uiverse.io by mrhyddenn - Tags: button, hover, glow */
.shadow__btn {
  padding: 10px 20px;
  border: none;
  font-size: 17px;
  color: #fff;
  border-radius: 7px;
  letter-spacing: 4px;
  font-weight: 700;
  text-transform: uppercase;
  transition: 0.5s;
  transition-property: box-shadow;
}

.shadow__btn {
  background: rgb(0,140,255);
  box-shadow: 0 0 25px rgb(0,140,255);
}

.shadow__btn:hover {
  box-shadow: 0 0 5px rgb(0,140,255),
              0 0 25px rgb(0,140,255),
              0 0 50px rgb(0,140,255),
              0 0 100px rgb(0,140,255);
}
</style>
